Before the patch, the flock flag could remain uninitialized for thelifespan of the fuse_file allocation. Unless set to true infuse_file_flock(), it would remain in an indeterminate state until read inan if statement in fuse_release_common(). This could consequently lead totaking an unexpected branch in the code.

The bug was discovered by a runtime instrumentation designed to detect useof uninitialized memory in the kernel.